I. Field
The following relates generally to wireless communication, and more specifically to allocation of multi-carrier wireless channels in a wireless communication environment.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content and services such as, e.g. voice content, data content, video content, packet data services, broadcast services, messaging services, multimedia services, and so on. Typical wireless communication systems can be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access systems can include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple mobile devices. Each mobile device can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations can be established via a single-in-single-out (SISO) system, a multiple-in-single-out (MISO) system, or a multiple-in-multiple-out (MIMO) system.
Wireless communication systems typically employ a particular carrier frequency for transmitting information. The carrier frequency chosen can depend on a type of the wireless system. For instance, cellular systems employ a government-licensed frequency spectra, whereas other systems (e.g. radio, WiFi, etc.) employ non-licensed spectra. In addition, bandwidth of the carrier frequency is related to an amount of data that can be conveyed in a period of time, also referred to as throughput or data rate.
Although a carrier bandwidth is generally fixed by a particular wireless system (e.g. 2 megahertz [MHz], 2.5 MHz, 5 MHz, and so on), multi-carrier systems have recently been developed to increase bandwidth for applications requiring high data rates. Furthermore, multi-carrier systems can yield improved resource utilization and spectrum efficiency by joint resource allocation and load balancing across the multiple carriers. In a multi-carrier system, a terminal can be allocated multiple carrier channels, which are aggregated by the terminal to increase the rate at which information is transmitted to or from the terminal. When traffic requirements for the terminal diminish, the additional carrier(s) can be released, freeing up a channel for other terminals.
As an example of the foregoing, multi-carrier high speed packet access (MC-HSPA) is an evolution of the HSPA systems, in which two 5 MHz carrier channels are aggregated to increase channel bandwidth, resulting in increased throughput and data rates. The MC-HSPA system is backward compatible for terminals designed with older protocols, such as the third generation partnership project (3GPP) Release 7 (R7), R6, R5, and Release '99 (R99). In addition, for operators the MC-HSPA system enables efficient and flexible spectrum asset utilization even though multiple carriers licensed to the operator are not contiguous within the frequency spectrum.
Despite the benefits, some problems associated with multi-carrier systems exist. First, terminals typically are required to demodulate or decode over multiple carriers, significantly increasing processor consumption. This has an adverse affect on battery life for the terminal. Furthermore, the terminal is often required to provide additional feedback information to a serving network, including downlink channel conditions and transmission results on each of the multiple carriers. Additional costs can be associated with multiple uplink carriers as well. Accordingly, a multi-carrier system that mitigates terminal battery drain while maintaining flexibility, throughput and reduced latency would provide a significant advantage over existing multi-carrier systems.